[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 250602 CCA
TWDAT

TROPICAL WEATHER DISCUSSION...CORRECTED
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN SEP 25 2005

...CORRECTED FOR DAY AND DATE...

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM
THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON
SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0500 UTC.

...SPECIAL FEATURES...

TROPICAL DEPRESSION RITA IS CENTERED NEAR 33.0N 93.9W...OR 35 NM
N OF SHREVEPORT LOUISIANA...AT 25/0300 UTC MOVING N 9 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 985 MB. MAXIMUM SUSTAINED
WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. THIS IS THE LAST
ADVISORY ISSUED BY THE NATIONAL HURRICANE CENTER ON RITA. SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/
WTNT23 AND FUTURE PUBLIC ADVISORIES ISSUED BY THE
HYDROMETEOROLOGICAL PREDICTION CENTER UNDER AWIPS/WMO HEADERS
TCPAT3/WTNT33 KWNH FOR MORE DETAILS. SURFACE OBSERVATIONS AND
RADAR IMAGERY INDICATE THAT THE CENTER OF RITA HAS MOVED INTO SW
ARKANSAS BUT THE MAIN RAIN SHIELD EXTENDS PRIMARILY FROM
S/CENTRAL ARKANSAS NWD INTO CENTRAL MISSOURI AND SRN
ILLINOIS...FROM THE MISSISSIPPI AND OHIO RIVERS WWD TO THE
ARKANSAS/OKLAHOMA BORDER. ONE SPIRAL RAIN BAND WITH GUSTY WINDS
AND POSSIBLE TORNADIC ACTIVITY CONTINUES TO EXTEND S OF THIS
RAIN SHIELD ALONG THE MISSISSIPPI RIVER FROM GREENVILLE TO
NATCHEZ MISSISSIPPI. RITA IS EMBEDDED IN STRONG SWLY FLOW ALOFT
AND SHOULD CONTINUE MOVING GENERALLY NE/E OVER THE NEXT SEVERAL
DAYS...LESSENING THE THREAT FOR EXCESSIVE RAINFALL AMOUNTS.
HOWEVER...ISOLATED AMOUNTS UP TO 15 INCHES IS STILL POSSIBLE
ESPECIALLY IN AREAS WHERE HEAVY RAIN BANDS TRAIN FOR LONG
PERIODS OF TIME.

A 1008 MB LOW IS CENTERED ABOUT 235 NM E OF BERMUDA NEAR 32N60W
MOVING ENE 10 KT. THE LOW IS SOMEWHAT COMPLEX AND MULTIPLE
SWIRLS...ONE WHICH IS THE REMNANT CIRCULATION OF T.D.
PHILIPPE...ARE ROTATING AROUND THE COMMON CENTER REFERENCED
ABOVE. THE SYSTEM IS LOCATED ON THE NW SIDE OF A LARGE UPPER
LEVEL ANTICYCLONE AND IS EXPERIENCING STRONG S/SWLY SHEAR AT THE
MOMENT WHICH IS DISPLACING THE DEEP CONVECTION WELL TO THE N
ALONG A STATIONARY FRONTAL BOUNDARY. SCATTERED MODERATE
CONVECTION FROM 34N-40N BETWEEN 47W-60W. THE LOW IS EXPECTED TO
REMAIN UNDER STRONG SWLY SHEAR FOR AT LEAST ANOTHER 36 HRS BUT
THEN MAY BECOME COLLOCATED WITH AN UPPER LEVEL LOW AND WEAKER
WINDS ALOFT. BECAUSE OF THIS...TROPICAL OR SUBTROPICAL
DEVELOPMENT OF THIS SYSTEM IS POSSIBLE WITHIN THE NEXT 36 HRS.

A 1008 MB LOW IS CENTERED ABOUT 600 NM WSW OF THE CAPE VERDE
ISLANDS NEAR 13N34W MOVING W 10 KT. THE LOW CURRENTLY HAS AN
ELONGATED CIRCULATION BUT A 2032 UTC QUIKSCAT PASS SHOWED A
CENTER NEAR 12N33W EXTENDING NE/SW. THE LOW IS ALSO LOCATED JUST
W OF A TROPICAL WAVE ALONG 40W...WHICH LIES ON THE W SIDE OF THE
DEEP CONVECTION. WIDELY SCATTERED MODERATE CONVECTION FROM
10N-16N BETWEEN 30W-40W. THE LOW IS LOCATED UNDER STRONG SLY
SHEAR ON THE E SIDE OF AN UPPER LOW CENTERED NEAR 14N47W BUT
THIS PATTERN MAY BECOME MORE CONDUCIVE FOR TROPICAL DEVELOPMENT
IN THE NEXT 36-48 HRS.

...TROPICAL WAVES...

SEE SPECIAL FEATURES FOR TROPICAL WAVE ALONG 40W.

EAST CARIBBEAN TROPICAL WAVE ALONG 64W S OF 20N MOVING W 15 KT.
SHORTWAVE INFRARED IMAGERY SHOWS A CLUSTER OF CLOUDS/CONVECTION
JUST W OF THE LESSER ANTILLES WHICH INDICATES THAT THE WAVE MAY
BE A LITTLE BIT FARTHER E THAN ANALYZED. IN ADDITION...UPPER AIR
DATA FROM GUADELOUPE AND TRINIDAD BOTH SHOW NELY FLOW AT 00 UTC
IN THE LOW AND MID-LEVELS WHICH SUGGESTS THAT THE WAVE HAD NOT
PASSED THE ISLAND CHAIN AT THAT TIME. SCATTERED MODERATE/
ISOLATED STRONG CONVECTION FROM 10N-16N BETWEEN 61W-66W. WIDELY
SCATTERED MODERATE IS ALSO MOVING ACROSS BARBADOS AND FROM
GUADELOUPE SWD TO ST. LUCIA.

TROPICAL WAVE ANALYZED ALONG 79W S OF 18N. RE-EVALUATION OF
SURFACE OBSERVATIONS AND SATELLITE IMAGERY INDICATE THAT THE
WAVE IS PROBABLY STILL FARTHER E ALONG 73W. SCATTERED MODERATE
CONVECTION FROM 8N-13N BETWEEN 71W-75W. WIDELY SCATTERED
SHOWERS/TSTMS FROM 16N-20N BETWEEN 72W-77W.

...ITCZ...

ITCZ IS CENTERED ALONG 6N10W 13N32W...THEN 9N41W 6N54W 12N70W
13N87W. WIDELY SCATTERED MODERATE CONVECTION WITHIN 120 NM OF
THE AXIS BETWEEN 10W-25W. WIDELY SCATTERED SHOWERS/TSTMS WITHIN
100 NM OF THE AXIS BETWEEN 41W-51W.

...DISCUSSION...

GULF OF MEXICO...
RITA HAS CONTINUED TO WEAKEN AS IT MOVES FARTHER INLAND TOWARDS
SW ARKANSAS. STRONG SLY FLOW CONTINUES TO FEED INTO THE
CIRCULATION YET THERE IS NOT ENOUGH LOW-LEVEL CONVERGENCE TO
SUPPORT MUCH IN THE WAY OF ANY TRAILING CONVECTION. A SMALL AREA
OF WIDELY SCATTERED MODERATE/STRONG CONVECTION HAS MOVED INTO
THE BAY OF CAMPECHE FROM 18N-21N BETWEEN 91W-94W.
OTHERWISE...EXTENSIVE CIRRUS OUTFLOW FROM RITA CONTINUES TO
EXPAND N AND E OF THE STORM WITH SOME OF IT FINDING ITS WAY SWD
OVER THE E HALF OF THE GULF. RADAR IMAGERY SHOWS ONLY A FEW
STRAGGLING TSTMS EXTENDING UP TO 50 NM OFFSHORE THE
ALABAMA/PENSACOLA FL COASTLINE MOVING NWD INTO SW ALABAMA. RITA
WILL CONTINUE MOVING N AND E ACROSS THE SOUTHEAST U.S. IN THE
COMING DAYS AND MODEL GUIDANCE SUGGESTS THAT A COLD FRONT COULD
MOVE INTO THE N GULF WITHIN THE NEXT 48 HRS. THIS WILL HAVE TO
BE WATCHED FOR POSSIBLE DEVELOPMENT OF LOW PRES ALONG THE
TRAILING END OF THE FRONT LATER IN THE WEEK.

CARIBBEAN...
THE TRADE WINDS HAVE ESSENTIALLY BROKEN DOWN OVER THE CARIBBEAN
WATERS AND MOST OF THE BUOY OBSERVATIONS AND QUIKSCAT DATA
INDICATE VARIABLE WINDS NEAR 5 KT IN THE E/CENTRAL PART OF THE
BASIN. AN UPPER LEVEL COL IS CENTERED S OF HISPANIOLA NEAR
16N74W AND THIS HAS SEPARATED THE AREA INTO TWO REGIMES OF NELY
FLOW TO THE W AND E/SE FLOW TO THE E. UPPER LEVEL CIRRUS IS
ABUNDANT W OF 70W BUT IT DOES APPEAR THAT STRONGER SUBSIDENCE IS
BEGINNING TO MOVE SWD ACROSS CUBA TOWARDS JAMAICA AND THE CAYMAN
ISLANDS. DEEP-LAYERED MOISTURE WILL REMAIN QUITE PREVALENT
ACROSS THE AREA OVER THE NEXT 5 DAYS...ESPECIALLY OVER THE W
CARIBBEAN...AND THIS SHOULD BE ABLE TO SUPPORT AREAS OF
SHOWERS/TSTMS FOR MOST OF THE UPCOMING WEEK.

ATLANTIC...
A NEARLY STATIONARY MID/UPPER LOW IS LOCATED JUST N OF THE SRN
BAHAMAS NEAR 24N73W AND CONTINUES TO DRAW DRIER AIR SWD OVER THE
W ATLC WATERS...SPREADING OVER PARTS OF SE FLORIDA...THE
BAHAMAS...AND CUBA. THE LOW IS ALSO DRAWING DEEP TROPICAL
MOISTURE NEWD OVER HISPANIOLA TO 27N67W WHICH IS PRODUCING
WIDELY SCATTERED SHOWERS/TSTMS WITH ISOLATED MODERATE CONVECTION
S OF 22N BETWEEN 65W-72W. A 1008 MB LOW...PARTLY THE REMNANTS OF
T.D. PHILIPPE...IS CENTERED NEAR 31N60W WITH A TROUGH EXTENDING
SW TO 27N67W. WIDELY SCATTERED MODERATE CONVECTION IS LOCATED
AHEAD OF THE TROUGH NEAR THE CONVERGENCE WITH THE SUBTROPICAL
RIDGE FROM 19N-28N BETWEEN 53W-58W. A LARGE UPPER LEVEL HIGH IS
CENTERED OVER THIS AREA NEAR 25N55W WITH A RIDGE EXTENDING FROM
THE NRN LEEWARD ISLANDS NEWD TO 32N51W. FARTHER E...A LARGE
UPPER LOW IS EMBEDDED DEEP WITHIN THE TROPICS NEAR 15N45W WITH A
TROUGH/SHEAR AXIS REACHING NEWD TO 30N32W AND IS PUMPING
TROPICAL MOISTURE NWD OVER A GOOD CHUNK OF THE E/CENTRAL ATLC.
HOWEVER...THIS FLOW IS ALSO PRODUCING STRONG SLY SHEAR OVER THE
LOW AND TROPICAL WAVE NEAR 35W AND CONTINUES TO IMPEDE TROPICAL
DEVELOPMENT. AN UPPER LEVEL LOW HAS MOVED OFF THE AFRICAN COAST
NEAR 14N20W MOVING SLOWLY W TOWARDS THE CAPE VERDE ISLANDS AND
COULD BE THE REFLECTION OF A NEW TROPICAL WAVE MOVING OFF THE
COAST.

$$
BERG



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